Controlling the Application Processors | Intel MultiProcessor

MultiProcessor Specification

A.2 Controlling the Application Processors

Provision must be made to prevent all processors from executing the BIOS after a power-on RESET. System developers may choose to do this by the hardware alone or by cooperation between hardware and the BIOS. In the latter case, the BIOS may be used for selecting the BSP and placing all APs to sleep after POST. The BIOS may use the APIC ID as a means by which to identify each processor and select the proper code sequence to execute. Only the selected BSP continues to load the operating system after the POST routine.

A.3 Programming the APIC for Virtual Wire Mode

The APICs do not require BIOS programming if the default interrupt mode at start-up is PIC Mode. Special programming is needed only if the startup interrupt mode is Virtual Wire Mode.

Because Virtual Wire Mode must run all existing uniprocessor software, the system BIOS must initialize and enable the BSP’s APIC first. The local unit must be programmed to function as a “virtual wire,” which delivers the CPU interrupt from the 8259A-equivalent PIC to the BSP via its local APIC.

The External Interrupt (ExtINT) delivery mode must be used so that the APICs and 8259A- equivalent PICs can function together in the same system. For interrupts that are programmed for ExtINT delivery mode, there is no need to issue an EOI to the APIC; only the 8259A PIC requires an EOI as usual. Also, because the 8259A delivers the vector to the processor for ExtINT delivery mode, the interrupt vector in the APIC’s redirection table is ignored.

To program the APIC to Virtual Wire Mode, the system BIOS must program the APIC to enable the LINT0 of the BSP’s local APIC for edge-triggered ExtINT delivery mode, and LINT1 for level-triggered NMI delivery mode. There is no need to program the I/O APIC if it is not used in Virtual Wire Mode.

Example A-1 is an example of programming the LINTIN0 and LINTIN1 to support Virtual Wire Mode.

A-2	Version 1.4

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Intel MultiProcessor manual Controlling the Application Processors, Programming the Apic for Virtual Wire Mode

Contents

MultiProcessor Specification Copyright 1993-1997. Intel Corporation, All Rights Reserved Revision History Revision Revision History DatePage Table of Contents Default Configurations MP Configuration TableContents Appendix B Operating System Programming Guidelines Appendix a System Bios Programming GuidelinesAppendix E Errata Glossary Figures Tables Examples Page Goals Conceptual Overview MultiProcessor Specification Features of the SpecificationScope Document Organization Target AudienceOrganization of This Document Introduction Conventions Used in This Document For More Information System Overview Hardware Overview System Processors Advanced Programmable Interrupt Controller System Overview System Memory 4 I/O Expansion Bus Bios Overview Operating System OverviewPage Hardware Specification System Memory Configuration System Memory Cacheability and Shareability System Memory Address Map Hardware Specification Memory Cacheability Map External Cache Subsystem Locking Multiprocessor Interrupt Control Posted Memory WriteApic Architecture Interrupt Modes Apic Versions PIC Mode PIC Mode Virtual Wire Mode Virtual Wire Mode via Local Apic Virtual Wire Mode via I/O Apic Symmetric I/O Mode Symmetric I/O Mode Floating Point Exception Interrupt Assignment of System Interrupts to the Apic Local UnitApic Memory Mapping Apic Interval Timers Apic Identification Reset Support System-wide Reset System-wide Init Processor-specific Init Support for Fault-resilient Booting System Initial State MP Configuration Table MultiProcessor Specification MP Floating Pointer Structure MP Configuration TableOffset Length Field Bytesbits in bits Description Information Byte MP FeatureOffset Length Field Bytesbits Bits Description Information Bytes MP Configuration Table Header MP Configuration Table Header MP Configuration Table Header Fields Base MP Configuration Table EntriesOffset Length Field Bytes Bits Description Length Entry Description Entry Type Code Bytes Comments Base MP Configuration Table Entry TypesProcessor Entries Apic Processor Entry Fields Family Model Stepping a Description Feature Flags from Cpuid InstructionIntel486 and Pentium Processor Signatures Bit Name Description Comments BUS Type Bus EntriesBUS ID String Bus Type String Values Bus Type String Description Apic Entry 3 I/O Apic Entries4 I/O Interrupt Assignment Entries I/O Apic Entry Fields I/O Interrupt Entry 10. I/O Interrupt Entry Fields 11. Interrupt Type Values Local Interrupt Assignment EntriesInterrupt Type Description Comments Destination Local Apic 12. Local Interrupt Entry FieldsDestination Local Apic ID LINTIN# Extended MP Configuration Table Entries System Address Space Mapping Entries 14. System Address Space Mapping Entry Fields 10. Example System with Multiple Bus Types and Bridge Types Bus Hierarchy Descriptor Entry Compatibility Bus Address Space Modifier Entry 12. Compatibility Bus Address Space Modifier Entry 16. Compatibility Bus Address Space Modifier Entry Fields Default Configurations Default Number Bus Discrete Apic ConfigurationsDefault Configurations Config Code CPUs Type Variant Schematic Default Configuration for Discrete Apic Default Configurations Integrated Apic Configurations Default Configuration for Integrated Apic Assignment of I/O Interrupts to the Apic I/O Unit Default Configuration Interrupt AssignmentsConfig INTINx Comments First I/O Eisa and IRQ13 All Local APICs Config LINTINx CommentsAssignment of System Interrupts to the Apic Local Unit Level-triggered Interrupt Support MultiProcessor Specification System Bios Programming Guidelines Bios Post Initialization Programming the Apic for Virtual Wire Mode Controlling the Application Processors Example A-1. Programming Local Apic for Virtual Wire Mode System Bios Programming Guidelines Constructing the MP Configuration Table NMI System Bios Programming Guidelines Page Operating System Boot-up Operating System Programming Guidelines Operating System Booting and Self-configuration Interrupt Mode Initialization and Handling Application Processor Startup Operating System Programming Guidelines Using Init IPI Using Startup IPI AP Shutdown Handling Handling Cache Flush Other IPI ApplicationsSpurious Apic Interrupts Handling TLB Invalidation Supporting Unequal Processors Page System Compliance Checklist Page Interrupt Routing with Multiple APICs Variable Interrupt Routing Fixed Interrupt Routing Multiple I/O Apic Multiple PCI Bus Systems Bus Entries in Systems with More Than One PCI BusI/O Interrupt Assignment Entries for PCI Devices INTD#Page Errata 126 System Address Space Mapping Entries System Address Space Entry Address Type 14. System Address Space Mapping Entry FieldsEntry Length Address Base Bus Hierarchy Descriptor Entry Space records must also be provided BUS Informationsd Parent BUS Glossary Glossary-2 Order Number